[svn-r19713] Purpose:

Fixed h5diff to handle variable-length strings in a compound dataset 
    correctly. Also variable-length string array in a compound dataset.
    Bug #1989.
    

Description:
    Garbage values were displayed when h5diff compared variable-length 
    strings (or string array) in a compound type dataset. 
    Merged from hdf5 trunk r19712.


Tested:
 jam (linux32-LE), heiwa (linuxppc64-BE)

tools/h5diff/testfiles/h5diff_530.txt

@@ -0,0 +1,11 @@
+
+file1     file2
+---------------------------------------
+    x      x    /              
+    x      x    /Compound_dset 
+
+group  : </> and </>
+0 differences found
+dataset: </Compound_dset> and </Compound_dset>
+0 differences found
+EXIT CODE: 0